Vias in printed circuit boards (PCBs) are a major cause of reflections. Not having the correct material dielectric constant (Dk) value for via modeling, results in via impedance to line impedance mismatch and hence reflections. Using conventional methods, measurement of Dk values may result in via impedance to line impedance mismatch by 5 Ohm or more, which may cause reflections and potentially eye failure for high-speed SerDes (Serializer/Deserializer). Thus, it is important to be able to correctly measure material Dk for vias.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.